witchmd

So I got a used 97 F150 4x2 4.2L form my cousin. He did not do much except make the car worse, so now I am trying to get the thing back is good condition. I recently replace the one cat and exhaust and decided to take the CE light. The codes I got were p0131 and p1131, cleared and then p0158. So i went to remove the O2 sensor and it looks to be either welded on or stripped. I want to replace it myself, but can not think of a way that does not involve a hacksaw. Any ideas? I was hoping to look at the vacuum lines soon because the idle sounds rough. Anything else I should consider?